1. Field of the Invention
The present invention relates to vegetation rotary cutting devices, and in particular to a cutting head for attachment to various brands of such devices.
2. Discussion of the Prior Art
Many manufacturers provide rotary cutting devices for cutting and trimming lawns, weeds, underbrush and the like. These devices typically use a string or line that rotates at a high rate of speed at the end of an elongated, hand-held device. The devices are typically powered by a gasoline engine for professional use, or an electric motor for use by home owners.
Due to the widespread use of such trimming devices, a market has emerged for third parties to supply replacement line and accessory cutting heads for the equipment owners. These replacement items offer advantages not found in the parts supplied by the original equipment manufacturers. For instance, the replacement items offered by third party suppliers cost less partly because of the high volumes afforded by a single accessory fitting many different brands and styles of trimmers. Third party suppliers have advanced trimmer technology by designing more efficient cross-sections on trimmer lines, and by providing serrated plastic blades for replacing trimmer lines to improve cutting performance. New attachment heads offer greater simplicity and ease of use.
Each of the serrated plastic blades of previously existing attachment heads is pivotably secured to the main body of the attachment head by a steel shoulder screw and lock nut. For example, please see U.S. Pat. No. 5,430,943 issued to Anthony L. Lee on Jul. 11, 1995, incorporated herein by reference. While this arrangement provides a secure means for fastening the blades, the shoulder screws and nuts are relatively expensive. This attachment method requires significant assembly time during manufacture, further increasing costs. The end user must take extra time and use tools when removing and installing blades. Even with lock nuts, the possibility of the shoulder screws loosening during operation exists, especially if not properly tightened by the user.
What is needed and is not provided by the prior art is a trimmer attachment head which provides a simple, inexpensive and reliable means for securing plastic blades to the main body of the head, enabling the user to change blades quickly without the need for tools.